Decommissioned 30 January 1946.
Laid up in the Pacific Reserve Fleet.
Recommissioned 6 July 1951.
Decommissioned 30 April 1954.
Laid up in the Pacific Reserve Fleet.
Recommissioned 5 May 1957.
Decommissioned 1 September 1962.
Stricken 9 October 1962.
Sunk as a target by USS Pomodon (SS 486) off San Diego, California.

26 Oct 1943USS Aspro (Cdr. H.C. Stevenson, USN) departed Pearl Harbour for the submarine training area. She returned later the same day.

24 Nov 1943USS Aspro (Cdr. H.C. Stevenson, USN) departed from Pearl Harbor for her 1st war patrol. She was ordered to patrol off Formosa. Aspro was escorted out by USS PC-597.

For the daily and attack positions of USS Aspro during this patrol see the map below. As no deck log is available (for the moment) positions were taken from the patrol report. Unfortunately the patrol report does not give daily noon positions.

28 Nov 1943USS Aspro (Cdr. H.C. Stevenson, USN) refuels at Midway. She departed for her patrol area after a few hours.

(All times are zone -10)
1840 hours - Sighted a steady white light bearing 000°. Closed to investigate. Radar picked up the target at a range of 10100 yards. The target was sighted from the bridge from a range of 6000 yards and appeared to be a 100 tons sampan. She was net fishing with all lights burning. Decided to go around and attack from the dark area of moon with the deck gun.

2046 hours - Commenced firing from 3000 yards. The second round hit forward of the sampan's deck house near the waterline. The sampan then extinguished her lights and the gun pointers were unable to see the target. Closed to 1700 yards but then the sampan opened up fire with her machine guns. Soon she opened fire with a larger gun. Another sampan was then seen ahead and closing rapidly. It was then decided to break off the action and retired at high speed.

0750 hours - Sighted a convoy of three ships with a tanker in the center of two freighters. Two destroyers were seen to be the escort, one ahead, one astern. Started attack.

0816 hours - In position 25°07'N, 122°33'E fired four bow torpedoes at the tanker thought to be of about 7500 tons. Had to go deep after iring to avoid one of the destroyers. Enemy course was 260°, speed 12 knots, range 1675 yards.

0819 hours - Heard a torpedo explosion.

0821 hours - Deth charging started. Four deth charges were dropped over the next four minutes. No damage was done to Aspro.

1432 hours - Returned to periscope depth. Nothing in sight.

17 Dec 1943During the night of 17/18 December 1943, USS Aspro (Cdr. H.C. Stevenson, USN), twice attacked a Japanese convoy damaging the Japanese army tankers Sarawak Maru (5135 GRT, built 1943) and another tanker (often stated to be named Tenei Maru but this can't be correct as this ship was only completed in 1944).

The convoy attacked by Aspro was made up of the above mentioned Sarawak Maru, the unidentifed tanker mentioned above as well as fleet tanker Ogura Maru No.2 (7311 GRT, built 1931) and merchant tanker Fushimi Maru No.3 (4289 GRT, built 1943), the cargo ships Batavia Maru (4393 GRT, built 1919), Nichirei Maru (5396 GRT, built 1943) and Hirota Maru (2922 GRT, built 1940) and eight other unidentified merchant ships. They were escorted by destroyer Shiokaze and minesweeper W-33 (all offsite links).

1835 hours - Sighted smoke on the same bearing during the evening twilight. Started radar tracking. It soon became apparent that we were astern of a convoy. Commenced end around. Position was 24°13'N, 125°31'E.

1930 hours - Radar picked up another group of ships ahead of the group being tracked. Commenced tracking this group. The leading group was zig-zagging with courses of 180° and 270° as extremes. Enemy speed was 12 knots. The after group was closing the forward group at 15 knots as to join.

1940 hours - Went to three engine speed.

1950 hours - A third group of ships was picked up by radar. A brief track indicated this group was closing from the northwestward. Continued tracking the leading group of ships.

1957 hours - Went to four engine speed.

2025 hours - Sighted the convoy from the bridge. Range was now 14000 yards to the nearest ships. All the ships were now operating as one unit, enemy speed 12 knots.

2130 hours - Continued tracking and gaining position ahead.

2205 hours - Now in a good position ahead. Turned towards for a surface attack.

2225 hours - In position 23°59'N, 124°42'E commenced firing a full bow salvo. Range was about 2500 yards. Actually due to an error in drill only five torpedoes were fired before Aspro was turned to bring the stern tubes to bear.

2226 hours - Fired the stern tubes at a large tanker that was overlapping with a transport vessel. Range was about 2500 yards.

2227 hours - Commenced clearing the area at high speed on the surface.

2230 hours - Sighted one of the transports going down bow first. Her stern was in the air. Range was about 1500 yards. She was turning towards Aspro as she sank. This was the largest ship of the convoy.

2231 hours - Observed a medium to large freigther going down with a 15 degree angle.

2232 hours - Observed a medium sized freighter rolling over to starboard, lay on her side for a moment, and then sink. Also observed a tanker astern to settle in the water and going down by the bow until her bow was awash. This tanker was later seen to be in tow of one of the freighters.

2305 hours - All tubes reloaded. The convoy had scattered to the eastward except for one group of four freighters and two escorts. The crippled tanker in tow was following these ships but was rapidly drawing aft. Commenced tracking.

18 December 1943
0149 hours - In a position ahead. Dived to radar depth and turned to close track.

0210 hours - Went to periscope depth (55 feet).

0229 hours - In position 23°31'N, 124°15'E fired three bow torpedoes at a freighter in the center of the convoy and three bow torpedoes at an overlapping freighter to the right and ahead. Ranges were about 2500 yards.

0230 hours - Saw an explosion and orange colored flame from one freighter. Sound reported high speed screws close aboard. Started to go deep. Four torpedo explosions were heard. Just before the periscope went under a ship was seen to turn toward Aspro.

0232 hours - Depth charging started but none were close. Depth charging lasted for about one hour. Set course to clear the area to the northwestward in the hope of being able to finish off the damaged tanker later but she was not seen again.

27 Dec 1943USS Aspro (Cdr. H.C. Stevenson, USN) attacked a small Japanese convoy with four torpedoes in position 26°20'N, 148°15'E. No hits were obtained. The targets could not be seen in the bad visibility. The torpedoes were fired by radar plot.

(All times are zone -9.5)
1920 hours - In position 26°16'N, 148°14'E obtained radar contact bearing 119°, range 16600 yards. Commenced tracking. Visibility was only 100 yards as it was raining very hard.

1950 hours - A small 'pip' was now seen astern of the main target, must be an escort vessel.

2010 hours - Range was now 700 yards but nothing could be seen. The enemy's course was between 270° and 300°, speed 9 knots.

2049 hours - In position 26°20'N, 148°15'E fired four stern torpedoes at the targets from 1700 yards and then cleared the area. No hits were obtained.

2054 hours - Heard five explosions at 20 second intervals.

2130 hours - The targets faded out on the radar screen at a range of 18000 yards.

15 Jan 1944Lt.Cdr. William Alfred Stevenson takes over command from his brother Cdr. Harry Clinton Stevenson who has developed problems with his eyesight during Aspro's 1st war patrol and was disqualified after an eye examination.

3 Feb 1944After a short training period at Pearl Harbor USS Aspro (Lt.Cdr. W.A. Stevenson, USN) departed from this base for her 2nd war patrol. She was ordered to patrol north of Truk, Caroline Islands. Aspro was escorted out by USS PC-580.

For the daily and attack positions of USS Aspro during this patrol see the map below. As no deck log is available (for the moment) positions were taken from the patrol report. Unfortunately the patrol report does not give daily noon positions.

7 Feb 1944USS Aspro (Lt.Cdr. W.A. Stevenson, USN) refuels at Midway. She departed for her patrol area after a few hours.

(All times are zone -10)
1106 hours - In position 12°42'N, 149°17'E picked up a sound contact. Secured from routining torpedoes and started to plane up to periscope depth.

1118 hours - At periscope depth. Observed tops of what appeared to be a sampan astern.

1121 hours - Identified the target as a large Japanese submarine. She bore identificatian 443 and a large Japanese flag on her conning tower. A large stucture was observed after her conning tower. Range was about 5000 yards. The turn count indicated a speed of 17 knots. Commenced approach.

1142 hours - Abandoned the hope of making a submerged approach. The enemy was opening the range rapidly and was zig-zagging at high speed.

1207 hours - Surfaced. The enemy could just be seen through the high periscope. No radar contact. Started an end around at flank speed on four engines just keeping the enemy in sight through the high periscope.

1545 hours - The enemy submarine started to smoke badly. It is believed he stopped his engines in preparation to dive.

1555 hours - Lost sight of the enemy. At this time he was at extreme range. Either a zig took him out of visibility range or he had dived. His base course was 155°, this was the course towards Truk.

1700 hours - The enemy was seen again through the high periscope.

1845 hours - Lost target through the periscope due to darkness. Started to close to radar range.

1855 hours - Picked up the target on radar at a range of 18000 yards. Closed to 10000 yards before reliable bearings could be obtained.

2012 hours - Had gained a position ahead of the target.

2154 hours - By now had determined the enemy's zig-zag plan. Closed to attack.

2223 hours - In position 10°23'N, 150°23'E fired four torpedoes from 2100 yards using radar ranges and bearings.

2224 hours - Saw and heard an exlosion shortly afterwards followed by a second. Radar reported that the target was disappearing from the screen. In the dim glow the bow of the enemy could be seen rising in the air and the enemy submarine was seen to sink by the stern. Heavy black smoke covered the area where the enemy had sunk.

2227 hours - Heard a violent explosion.

2235 hours - Continued to our patrol area.

4 Mar 1944USS Aspro (Cdr. W.A. Stevenson, USN) attacked a large escorted transport vessel or tender to the north-east of Truk. Six torpedoes were fired but no hits were obtained. Aspro then chased the target but was unable to attack again.

1935 hours - Secured charge on one engine, went ahead on three engines.

2043 hours - Went ahead at flank speed on four engines.

2337 hours - Now in a position ahead of the target. Decided to make a surface approach from the dark side of the horizon.

4 March 1944
0110 hours - Range was now 10400 yards according to the radar. We were ahead on the far side of the target.

0122 hours - In position 09°12'N, 153°38'E fired six bow tubes from a range of 3350 yards.

0125 hours - A violent explosion occured which shook Aspro considerably. Nothing was however seen on the target that indicated a torpedo hit. The target began to circle and the escort closed her.

0127 hours - Heard the first of five end of run torpedo explosions.

0133 hours - Started reload. Continued to track the target. For the moment the target was stopped.

0154 hours - Started to close the target. The escort had opened up rom the target in the general direction of Truk.

0203 hours - Reload completed. Continued to close the target at flank speed on four engines. The target had gotten underway and was on a northeasterly course.

0210 hours - Lost contact with the escort at a range of 14500 yards.

0238 hours - Range is now 3600 yards.

0244 hours - The target turned away on a course of 030°. The targets speed was 17 knots. We followed in the targets wake and were able to close slowly at flank speed on four engines.

0314 hours - When the range had closed to 2850 yards the target opened fire with his after deck gun. We had to abandon the chase and dive. The first salvo landed even with the bow but to port. When the quartermast closed the conning tower hatch he observed a red flash overhead followed by the sound of an explosion.

0315 hours - While diving depth control was lost and Aspro broached but was taken down again. Went to 400 feet.

28 Mar 1944USS Aspro (Cdr. W.A. Stevenson, USN) ended her 2nd war patrol at Pearl Harbor. She was escorted in by USS PC-578.

Aspro then commenced refit by USS Proteus. She was also docked and sound tested. Refit was completed on 14 April 1944. Between 16 and 18 April 1944 she conducted training.

22 Apr 1944USS Aspro (Cdr. W.A. Stevenson, USN) departed from Pearl Harbor for her 3rd war patrol. She was ordered to patrol off the Palau's. She was escorted out by USS PC-1077.

For the daily and attack positions of USS Aspro during this patrol see the map below. As no deck log is available (for the moment) positions were taken from the patrol report. Unfortunately the patrol report does not give daily noon positions.

26 Apr 1944USS Aspro (Cdr. W.A. Stevenson, USN) refuels at Midway. She departed for her patrol area after a few hours.

0737 hours - Both ships are visible. The damaged ship was down by the stern. Both ships were dead in the water. The escorts could not be seen but pinging could be heard and they were searching. A plane was circling overhead.

0820 hours - The damaged ship was further down by the stern. The bow was at an angle of 35 to 40°. The aircraft was still circling overhead.

0845 hours - The damaged ship continued to settle by the stern. No attempt was being made to get her in tow. Went to 150 feet when the aircraft came towards.

0848 hours - A bomb explosion but not close and possibly not for us.

0900 hours - Heard explosions coming from the direction of the damaged ship.

0925 hours - At periscope depth. Only one ship could be seen. She was still lying too. The other ship must have sunk. The aircraft was still patrolling overhead.

0935 hours - The ship was now seen to be underway. Course 300°.

1055 hours - Lost contact with the freighter.

1400 hours - Lost contact with the smoke.

1842 hours - Surfaced. Went ahead at flank speed on two engines to regain contact with the remaining freighter.

1935 hours - Flank speed on three engines.

2058 hours - Flank sppeed on four engines.

2200 hours - In position 09°38'N, 132°03'E made radar contact, bearing 339°, range 26700 yards. Started an end around.

See 15 May 1944 for the continuation of these events.

15 May 1944USS Aspro (Cdr. W.A. Stevenson) torpedoed and sank the Japanese troop transport Jokuja Maru (6440 GRT, built 1944) about 175 nautical miles north-west of Palau in position 10°10'N, 131°48'E.

(All times are zone -9)
Continuation of the events of 13 and 14 May 1944
0014 hours - The range to the target had inreased to 28000 yards. Aspro tried to close but could not do so due to the escort.

0159 hours - Range to the freighter was now 22000 yards.

0210 hours - The escort appeared again at a range of 12500 yards. It looked like this was a radar equipped ship. Turned away to open the range.

0223 hours - Turned towards the target.

0225 hours - Dove to radar depth and commenced approach.

0246 hours - Went to periscope depth.

0308 hours - In position 10°10'N, 131°25'E fired four torpedoes from the stern tubes from a range of 1800 yards. Aspro went deep on firing as an escort was heard to speed up.

0310 hours - It is thought two hits were obtained.

0315 to 0325 hours - 12 depth charges were dropped. None were very close. Aspro meanwhile was at 400 feet and kept all the escorts abaft the beam.

0631 hours - Three depth charges were dropped. Not close. The ship was seen to be down by the stern and had a slight starboard list.

0729 hours - The damaged ship was seen to continue to settle and the list was seen to have increased. The escorts were seen to search the area.

0825 hours - The three escorts could be seen, they were conducting a search to the west of the target. Sighted a plane circling the target. The ship was slowly but definitely settling. Decided to continue approaching from the eastward and to finish the job with a couple of torpedoes from the bow tubes.

0936 hours - In position 10°10'N, 131°25'E fired two bow tubes from 3400 yards. Went to 400 feet immediately after firing and changed course 90° to get off the torpedo tracks.

0941 hours - Two explosions were heard, most likely end of run explosions. Later it was thought that the range had been underestimeted and that it were hits after all.

14 Jun 1944USS Aspro (Cdr. W.A. Stevenson, USN) entered Exmouth Gulf, Australia to take on board some fuel. She departed for Fremantle after a few hours.

16 Jun 1944USS Aspro (Cdr. W.A. Stevenson, USN) ended her 3rd war patrol at Fremantle, Australia. She was escorted in by USS SC-739. Refit was commenced by submarine division 122 relief crew and was completed on 30 June 1944.

9 Jul 1944USS Aspro (Cdr. W.A. Stevenson, USN) departed from Fremantle for her 4th war patrol. She was ordered to patrol in the South China Sea.

For the daily and attack positions of USS Aspro during this patrol see the map below. As no deck log is available (for the moment) positions were taken from the patrol report. Unfortunately the patrol report does not give daily noon positions.

19 Jul 1944USS Aspro (Cdr. W.A. Stevenson, USN) attacked a Japanese convoy of four merchant vessels and five escorts in the Molucca Sea in position 02°20'S, 126°37'E. No hits were obtained.

The convoy attacked was most likely made up of the Japanese transports Celebes Maru (5857 GRT, built 1917), Taian Maru (5492 GRT, built 1921), Taikai Maru (2508 GRT, built 1919) and Toyo Maru (2725 GRT, built 1943) and was escorted by the Japanese minesweepers W 5 and W 8 and the Japanese submarine chaser Ch-60 (all offsite links). The convoy was en-route from Bitung, Celebes, Netherlands East Indies to Ambon.

(All times are zone -8)
0220 hours - In position 02°20'S, 126°37'E obtained contact with the SJ radar bearing 083°, range 15500 yards. Lost contact several times due to the extreme range. There were four or five contacts close together.

0259 hours - Regained contact bearing 109°, range 16200 yards. Maintained contact and commenced tracking. The convoy was on a southeasterly course. Went ahead at flank speed to obtain a position ahead. It appeared the convoy was en-route to Ambon.

0410 hours - Reached a position ahead of the convoy, range was 15000 yards. As there was now not enought time left to make a night surface attack decided to attack from periscope depth at dawn.

0450 hours - Sighted the enemy convoy. Four fairly good sized ships were observed. Two were smoking quite heavily.

0510 hours - Heard pinging in the direction of the convoy.

0511 hours - Submerged and commenced approach.

0545 hours - Fired four bow torpedoes at the second transport from the left in the convoy. Range was 1800 yards. It is thought three hits were obtained on this ship.

0546 hours - Fired the remaining two bow torpedoes at the third transport. Range was 1450 yards. Swung to the right to bring the stern tubes to bear.

0547 hours - Fired four stern torpedoes from a range of 2300 yards. Went deep after firing the last torpedo. It is thought three of the stern torpedoes hit.

0551 hours - Depth charging started. A total of 9 were counted but none was very close.

0705 hours - Returned to periscope depth. Saw one of the escorts patrolling the area. It is thought two of the four tansports in the convoy were sunk.

20 Jul 1944USS Aspro (Cdr. W.A. Stevenson, USN) attacked an escorted Japanese transport ship north of Taliabu Island, Netherlands East Indies in position 01°34'S, 124°51'E. No hits were obtained. Following the attack Aspro was depth charged but sustained no damage.

0956 hours - Sighted black smoke on the same bearing as the pinging. Started approach. The contact was close inshore.

1022 hours - Sighted masts.

1106 hours - The contact was now seen to be a medium seized freighter with two escorts, one ahead and one astern of the freighter. They were zigging every five minutes.

1127 hours - Fired four bow torpedoes at the freighter from 1350 yards. Due to an error in drill the setup of the attack was incorrect.

1129 hours - Lt.Cdr. Stevenson saw, though surprised, that the target was obscured by smoke and spray. No hit had been heard but it seems likely that the target was damaged. An escort was seen coming towards at speed. Went to 450 feet.

1152 hours - A single depth charge was dropped. All depth charges were close but above Aspro. No damage was sustained by her. Aspro was underneath a gradiant at 450 feet and the escort was pinging in vain. When Aspro returned to periscope depth th escort that had been astern was seen about 4000 yards off keeping a listening watch. The target and the other escort were seen to clear the area close inshore.

0610 hours - Lost contact with the pinging and sight contact with the patrol vessel.

0929 hours - In position 18°19'N, 120°29'E sighted two freighters we had seen the day before and had chased for a while. Started approach. They were of 3000-4000 tons and 1500 tons.

1016 hours - Fired three bow tubes at the leading and larger freighter. Range was 1700 yards.

1017 hours - Observed the torpedoes running, one was leaving a trial of smoke. Lowered the periscope and started to turn to open out. Aspro was not in a position to attack the second target.

1018 hours - Observed the target turning towards.

1021 hours - Heard a torpedo explosion, most likely when it hit the beach.

1045 hours - Observed the target still underway but with a list to port of about 15°. Maybee a hit after all although a torpedo should have sunk this ship.

1103 hours - An aircraft was seen coming towards. Went to 150 feet.

1113 hours - Returned to periscope depth.

1120 hours - In position 18°19'N, 120°27'E sighted a patrol vessel in the direction of the pinging heard earlier. She was closing the freighter just attacked. The second freighter meanwhile had passed the freighter attacked. Also sighted smoke bearing 350°.

1132 hours - In position 18°19'N, 120°26'E sighted the tops of at least ten ships. Started an approach on these ships at 85 feet. Speed 7.5 knots.

1221 hours - Identified the contact as a large convoy of at least 17 vessels. They were giving the location of the recent attack a wide berth. Several tankers and large freighters were observed. An aircraft was circling the convoy. A 'Wakatake-class' destroyer was about 7000 yards distant conducting an echo ranging search. The patrol vessel that had closed our earlier target meanwhile was conducting a search close to the beach. Continued to close the convoy at periscope depth.

1426 hours - Range to the nearest ship in the convoy was now about 8000 yards. Aspro was however abaft the beam of the convoy and unable to close any further. There appeared to be as many escorts as ships in the convoy. Discontinued approach.

1910 hours - Surfaced. Went ahead flank speed on two engines. Started an end around.

2241 hours - Made sight contact with several ships of the convoy at an estimated range of 21000 yards. Still unable to pick up the convoy on radar.

2320 hours - Heard echo ranging. Made a sight contact with an escort on the same bearing. Range was 12000 yards.

2326 hours - Made radar contact with one of the ships of the convoy at a range of 17500 yards. This appeared to be the limiting range of our SJ radar at the moment. The set was not functioning properly.

2342 hours - Sighted an escort vessel on the starboard beam. Also heard echo ranging. Also picked up radar interference.

2351 hours - Escort evidently detected us because he headed in our direction. Turned away and went ahead flank speed on four engines. The range however remained the same 12000 to 14000 yards however we never had radar contact. He lost us against the land back ground and Aspro managed to work round him.

See 7 August for the continuation of the events.

7 Aug 1944USS Aspro (Cdr. W.A. Stevenson, USN) attacked a large Japanese convoy off the west coast of Luzon, north of Lingayen Gulf in position 17°12'N, 119°56'E. She claims to have sunk a freighter and damaged another one but this does not appear to be the case.

(All times are zone -8)
Continuation of the events of 6 August 1944
0140 hours - Made sight contact with several ships of the convoy.

0158 hours - Aspro was now 18000 to 20000 yards ahead of the convoy. An escort was ahead of the convoy. Range to this escort was 12000 yards.

0201 hours - Dived as an aircraft that had been sighted earlier over the convoy suddenly came towards. Range to this aircraft on diving was 6000 yards.

0241 hours - Observed the convoy zig towards us. 12 large merchant vessels were counted, possibly even more. The closest escort on diving was still the nearest ship.

0246 hours - The escort started pinging and headed towards.

0248 hours - Went deep when the range to the escort was only 2000 yards.

0304 hours - Returned to periscope depth. Visibility had decreased. The convoy could be seen but ranging was difficult. In the first group of six ships there were three or four tankers. The second group consisted of six to seven large to medium freighters. The escort that forced Aspro down was still the closest escort. Several other escorts were observed closer to the convoy.

0314 hours - The closest escort started closing and pinging in Aspro's direction on short scale.

0318 hours - The escort started to speed up and coming towards. Went to 400 feet. Aspro found a temperature gradiant to hide under and the escort lost contact.

0332 hours - Started to return to periscope depth.

0340 hours - At periscope depth. Observed the convoy astern. The closest ship, a large freighter was at a range of 3200 yards.

0345 hours - In position 17°12'N, 119°56'E fired four stern torpedoes at the center ship of a group of six or seven overlapping freighters from a range of 3500 yards.

0349 hours - Heard a torpedo explosion. 20 seconds later heard and saw a torpedo hitting the center ship. There was a large volume of water amidships. The ship sagged in the middle like it's back was broken and started to settle. The bow was seen to rise at an angle of 30 degrees and the ship was seen no more.

0350 hours - Several of the crew heard another torpedo explosion.

0351 hours - One torpedo could still be heard running.

0352 hours - Observed another freighter smoking. It is thought this ship was hit by the third torpedo.

0353 hours - Started to clear the area.

11 Aug 1944At 1207 hours (zone -8), USS Aspro (Cdr. W.A. Stevenson, USN), was detected by an enemy aircraft in the Makassar Strait in position 03°13'S, 118°28'E. Aspro crash dived and was strafed by the enemy while passing 38 feet. The aircraft had not been detected by the SD radar.

10 Sep 1944USS Aspro (Cdr. W.A. Stevenson, USN) departed from Fremantle for her 5th war patrol. She was ordered to patrol in the South China Sea.

For the daily and attack positions of USS Aspro during this patrol see the map below. As no deck log is available (for the moment) positions were taken from the patrol report. Unfortunately the patrol report does not give daily noon positions.

17 Sep 1944USS Aspro (Cdr. W.A. Stevenson, USN) topped up with fuel at Darwin, Australia. Aspro was escorted in by HMAS ML 813 (T/Lt. J.S. Berge, RANVR). She departed for her patrol area after only a few hours in port.

20 Sep 1944At 1714 hours (zone -8), USS Aspro (Cdr. W.A. Stevenson, USN), stopped a sampan after firing warning shots. As it was a native craft with 6 very scared natives on board the were given bread, cigarettes, etc and were allowed to proceed. No information could be received from them as they spoke no English at all. Position was 06°05'S, 119°12'E (Flores Sea).

30 Sep 1944USS Aspro (Cdr. W.A. Stevenson, USN) claims to have sunk a Japanese merchant vessel from a Japanese convoy off the west coast of Luzon.

(All times are zone -8)
1025 hours - In position 17°03'N, 120°21'E sighted smoke to the northeast and and heard pinging in that direction. Started closing.

1043 hours - Identified the contact as a convoy of 7 or possibly 8 merchant vessels exclusive the escorts. Sound reported at least 4 sets of echo ranging. Continued to close at 150 feet at 8 knots. Came to periscope depth every 15-20 minutes for a look.

1120 hours - Sighted two aircraft over the convoy.

1238 hours - In position 17°01'N, 120°25'E fired 6 bow tubes at a large freighter wich was overlapping with another freighter behind. Range was 1700 yards.

1240 hours - Heard two torpedo explosions.

1242 hours - Depth charging started. A total of 43 were counted.

1255 hours - Heard breaking up noises for about 15-20 minutes.

1318 hours - Started to come up to periscope depth.

1321 hours - Heard a loud exlosion. Went deep again to reload.

1355 hours - At periscope depth. Three aircraft were seen flying low over the convoy. The tops and smoke of 6 merchant vessels was seen. Nothing could be seen in the place of the attack but echo ranging was heard on that bearing for the next hour.

1535 hours - An aircraft was flying on our port beam. She was in a dive. Went to 150 feet.

1605 hours - At periscope depth. An escort vessel was seen to be coming towards at a range of 7000 yards. The aircraft must have seen us and asked one of his friends over. Went deep.

1635 hours - An escort vessel was heard to cross our stern. A second escort was also heard to be close. Aspro was however not detected.

1 Oct 1944While trying to attack a small northbound Japanese convoy off the west coast of Luzon, USS Aspro (Cdr. W.A. Stevenson, USN), grounded multiple times spoiling all the efforts to fire torpedoes at this convoy.

(All times are zone -8)
1232 hours - In position 17°34'N, 120°19'E sighted smoke and masts of two ships. One was identified as a trawler, the other was an engine-aft medium tanker. Commenced approach.

1238 hours - Sighted another merchant ship.

1300 hours - The trawler was about 5000-6000 yards ahead of the two merchant vessels.

1302 hours - Went to 200 feet to let the trawler pass overhead.

1312 hours - At periscope depth. Made a setup on the tanker.

1325 hours - Aspro hit bottom and came up to 45 feet. Backed full and blew ballast, Aspro then pulled clear. Aspro then dived again to 85 feet. Both ships continued on their way.

1333 hours - A depth charge or aircraft bomb exploded followed by two more a minute later.

1335 hours - Hit bottom again and came up to 70 feet. Backed off again and went to 100 feet.

1344 hours - Two depth charges were dropped.

1349 hours - Grounded again in 80 feet. Aspro could not get to periscope depth as she had lost trim. She could not get off. Screws were heard from time to time. Decided to wait a while.

1350 hours - A depth charge exploded.

1358 hours - Backed out again and tried to get to periscope depth. Again this was not succesful.

1404 hours - Another depth charge exploded. This must be an aircraft.

1425 hours - Started to rise after pumping out water.

1429 hours - Grounded yet again in 70 feet. Backed full and Aspro broached. Only a sampan and the two merchant vessels that were going away could be seen so surfaced.

1430 hours - A bi-plane was sighted circling. Aspro was still kicking up mud aft.

1432 hours - Dived when the aircraft made his dive towards.

1433 hours - A bomb went off when Aspro was passing 50 feet but it was not very close. Continued to open out from the coast in search for deeper water. Stayed submerged for the remainder of the afternoon. Surfaced after dark. Took up a position on the coast as to intercept today's contact the next morning.

Aspro sustained only some damage to her sound heads during these groundings.

2 Oct 1944USS Aspro (Cdr. W.A. Stevenson, USN) claimed to have sunk a Japanse tanker in position 18°25'N, 120°32'E. A Japanese freighter (Azuchisan Maru (6886 GRT, built 1944)) was damaged in the same position.

(All times are zone -8)
0538 hours - In position 18°11'N, 20°23'E sighted a ship bearing 100°. Identified this as yesterday's tanker.

0545 hours - Sighted the freighter ahead of the tanker. The escorting trawler was also seen. Started approach at 100 feet. Took a look through the periscope ever 25 minutes.

0905 hours - Saw the freighter at a range of 3400 yards. Started approach.

0920 hours - The freighter (5000 to 6000 tons) was stopped with a small boat alongside. There was an aircraft circling the freighter.

0950 hours - Manouvered into position for a stern tube shot.

0955 hours - In position 18°25'N, 120°32'E fired three torpedoes from the stern tubes from 1800 yards.

0957 hours - Heard two torpedo explosions 33 seconds apart.

0958 hours - One aircraft bomb was dropped.

0959 hours - Two aircraft bombs were dropped.

1001 hours - One aircraft bomb was dropped. This one was close.

1009 hours - At periscope depth. The freighter was slighly down by the stern. The ship appeared to be underway.

1012 hours - One aircraft bomb was dropped, close. Observer the plane, a medium bomber, bank and head in again. Went to 150 feet. As the battery was very low Lt.Cdr. Stevenson decided that it was not possible to make another attack and he set course to retire from the coast.

0913 hours - Identified the freighted as the one we had damaged yesterday. Hit anchor chain was out. It was quite possible that he dragged anchor during the night.

0929 hours - Fired two torpedoes from the stern tubes from 2200 yards. Both hit.

0955 hours - As the target was not sinking decided to fire another torpedo at it so fired a torpedo from No.1 tube from 1500 yards. It hit. The target began to settle aft but did not appear to be sinking fast enough.

0958 hours - Fired a torpedo from No.2 tube from 1450 yards. This torpedo was not needed anymore as the bow of the target suddenly rose in the air and she started to sink rapidly. Took periscope pictures of the sinking.

1002 hours - The target had gone under now. Position was 17°56'N, 119°52'E.

6 Oct 1944USS Aspro (Cdr. W.A. Stevenson, USN) attacked a tanker in large Japanese convoy to the north of San Fernando, Luzon, Philippines in position 16°53'N, 120°18'E. Three torpedoes were fired but no hits were obtained.

(All times are zone -8)
0615 hours - Sighted smoke to the south though to be coming from a northbound convoy.

0650 hours - In position 16°53'N, 120°19'E sighted the tops of at least 7 ships. A float plane was circling overhead. Started approach.

0711 hours - We were on the convoy's track. Range was 12000 yards. A small escort was seen 7000 yards ahead of the convoy.

0725 hours - Went to 200 feet to pass under this leading escort now about 2000 yards away.

0728 hours - The escort speeded up and dropped three depth charges which were close. Went to 350 feet.

0747 hours - Started to come up.

0754 hours - The convoy had zigged away.

0809 hours - Went to 250 feet to close the convoy again.

0828 hours - At periscope depth. The convoy had zigged back on it's original course and we were now inside the convoy. Brought all torpedo tubes to the ready.

0829 hours - Put up the periscope for final set up. Heard strafing of machine gun fire.

0830 hours - In position 16°53'N, 120°18'E started firing the three remaining stern torpedoes at a tanker from 1700 yards. Again strafing of machine gun fire was heard. Went deep.

0832 hours - In the after torpedo room they heard a torpedo hit.

0837 hours - Depth charging started. A total of 14 were counted.

0846 hours - Two depth charges were dropped.

0913 hours - Started to come up to periscope depth.

0922 hours - At periscope depth. Counted 12 merchant vessels and 4 escorts (there may have been more). One escort remained nearby for the remainder of the morning.

7 Oct 1944USS Aspro (Cdr. W.A. Stevenson, USN) torpedoed and sank the Japanese transport Macassar Maru (4026 GRT, built 1920) off the west coast of Luzon, Philippines in position 17°54'N, 119°57'E.

The above mentioned Macassar Maru was part of convoy TAMA-28 that was made up of Chosan Maru (3938 GRT, built 1940), Muroran Maru (5354 GRT, built 1919), Fuyukawa Maru (2845 GRT, built 1944), Shinsei Maru (4734 GRT, built 1917) and Taisei Maru (2288 GRT, built 1904). They were escorted by the Japanese frigates Daito and Yashiro, patrol boat Patrol Boat No.104, submarine chaser Ch-21 and auxiliary submarine chasers CHa-87 and CHa-92 and auxiliary gunboat Hua Shan Maru (all offsite links).

(All times are zone -8)
0310 hours - In position 17°46'N, 120°04'E made radar contact with the convoy reported by USS Hoe at a range of 23400 yards. Commenced tracking.

0415 hours - Ordered by Hoe to make an attack from the starboard side of convoy. At that moment Aspro was on the port bow of the convoy.

0435 hours - Received a message from Hoe that she had made an attack.

0450 hours - Went to radar depth.

0455 hours - Went to 60 feet. Selected a large merchant vessel as the target. Range was 3000 yards.

0456 hours - In position 17°54'N, 119°57'E fired four torpedoes from 2700 yards. Three hits were heard but were not observed.

0459 hours - Observed the target to be down by the stern. The target was soon seen to settle.

0501 hours - Had to go deep as an escort was approaching. 9 Depth charges were dropped but none were close. Depth charging continued all morning but the escorts were never in contact and their depth charges were not close.

Aspro remained in contact with the convoy but as she had no torpedoes left she departed from the patrol area the next day after USS Hoe had regained contact with the convoy.

25 Oct 1944USS Aspro (Cdr. W.A. Stevenson, USN) arrived at Pearl Harbor ending her 5th war patrol. She was escorted in by PC-579. Refit was commenced by the Pearl Harbour submarine base and by submarine division 43 relief crew and was completed on 10 November 1944. During this refit Aspro was docked. Post refit trials were undertaken during 10 to 13 November 1944. Training was undertaken during 14 to 18 November 1944.

21 Nov 1944USS Aspro (Cdr. W.A. Stevenson, USN) departed from Pearl Harbor for her 6th war patrol. She was at first to proceed to Saipan before proceeding to her patrol area off Formosa.
Aspro was escorted out by USS PC-571.

28 Nov 1944USS Aspro (Cdr. W.A. Stevenson, USN) suffers engine problems and is forced to return to Pearl Harbor for repairs at these could not be undertaken at Saipan.

3 Dec 1944USS Aspro (Cdr. W.A. Stevenson, USN) arrived back at Pearl Harbour. She was escorted in by USS PC-580.

13 Dec 1944After engine repairs USS Aspro (Cdr. W.A. Stevenson, USN) departed from Pearl Harbor to resume her 6th war patrol. She was ordered to patrol off Formosa and also to perform lifeguard duties during air strikes. She was escorted in by USS PC-485.

For the daily and attack positions of USS Aspro during this patrol see the map below.

2 Jan 1945USS Aspro (Cdr. W.A. Stevenson, USN) torpedoed and damaged the Japanese landing craft depot ship Shinshu Maru (8170 GRT, built 1935) in the southern part of the Formosa Strait in position 22°42'N, 119°14'E. The damaged Shinshu Maru is sunk the next day by aircraft from the US Task Force 38.

The above mentioned Shinshu Maru was in convoy MATA-40 together with landing craft depot ships Kibitsu Maru (9574 GRT, built 1943) and Hyuga Maru (9687 GRT, built 1944) and were escorted by the Japanese frigates Kanju, Nomi, Miyake, Ikuna, Kaibokan 112 and one other unidentified Japanese warship. They were en-route from North San Fernando, Philippines to Takao, Formosa (all links are offsite links)

(All times are zone -9)
0406 hours - In position 22°20'N, 118°40'E obtained radar contact bearing 010°, range 24750 yards. Started tracking. Started end around going flank speed on four engines. The convoy was made up of two large targets with three escorts. Enemy course was 050° at a speed of 10 knots.

0630 hours - By now Aspro was ahead of the convoy.

0700 hours - Submerged, started attack.

0715 hours - In position 22°42, 119°14'E started fired six torpedoes from the bow tubes from 900 yards. Actually only four torpedoes were fired as Aspro was taken to 150 feet after the fourth torpedo had been fired. About 50 seconds after firing the first toredo a torpedo hit on the target was heard.

0721 hours - Two deth charges were dropped, close.

0724 hours - Aspro was now at 190 feet.

0725 hours - A single depth charge was dropped but it was not close.

0817 hours - Returned to periscope depth. Distant pinging was heard astern. It now became clear that the torpedo in No.1 tube ran hot in the tube before leaving and that the torpedo in No.5 tube did not run. Decided to get red of all the three torpedoes now left in the bow tubes.

1046 hours - Attempted to eject the torpedo in No.5 tube. Most likely the forward part of the torpedo had broken off as the outer door could now be closed a bit further.

1900 hours - Surfaced while backing with a down angle. Fired No.5 tube and the remainder of the torpedo was forced out. The tube cleared and the outer door could be closed.

5 Jan 1945USS Aspro (Cdr. W.A. Stevenson, USN) claims to have sunk a damaged tanker to the south-west of Formosa in position 21°57'N, 119°44'E.

(All times are zone -9)
2158 hours - In position 21°43'N, 119°00'E obtained contact with SJ radar at a range of 24600 yards. Started tracking.

2214 hours - Target tracked at zero speed. Headed for the target.

2226 hours - Picked up a second contact on the SJ radar at a range of 12600 yards. This second contact was 4000 yards closer to us and was apparently an escort and was patrolling back and forth to the west of the stopped ship. Decided to work around to the east and approach from that direction.

2330 hours - In position 21°57'N, 119°44'E commenced firing four torpedoes from the bow tubes at a ship identified as a large damaged tanker. Range was 2500 yards. Two hits were obtained.

The tanker started to smoke heavily and several fires below had been started, but the pip on the radar remained the same size. The escort was about 5000-6000 yards from the damaged ship, still opening the range on a southwesterly course.

2341 hours - Started to close the damaged tanker.

2349 hours - At a range of 2000 yards the tanker sank, the pip disappeared from the radar screen and nothing remained but smoke.

6 Jan 1945USS Aspro (Cdr. W.A. Stevenson, USN) attacked a merchant vessel in a Japanese convoy to the south-west of Formosa. Four torpedoes were fired but no hits were obtained.

(All times are zone -9)
1451 hours - In position 21°48'N, 120°00'E sighted smoke on the horizon bearing 170°.

1454 hours - Sighted two ships with one escort through the high periscope.

1525 hours - Sound reported fast screws bearing 330°. The tops of another ship could be seen on this bearing. This was another escort joining the convoy.

1556 hours - In position 21°55'N, 119°55'E commenced firing the torpedoes from the stern tubes at a small freighter from a range of about 3000 yards. No hits were obtained. A few depth charges were dropped following this attack but these caused no damage to Aspro.

(All times are zone -9)
0355 hours - In position 35°01'N, 140°04'E sighted smoke on horizon followed by the sighting of masts of several small vessels rounding Nojima Saki lighthouse.

0427 hours - The contact developed into two heavily smoking tugs towing a dredger. Decided to fire two torpedoes at the largest tug thought to be of 400-500 tons.

0618 hours - In position 34°57'N, 140°04'E fired two torpedoes from a range of about 750 yards. The first torpedo hit amidships tearing a large hole in her side underneath her stack. Took pictures through the periscope.

0621 hours - The target rolled over and sank. The other tug picked up the survivors and went alongside the dredge.

3 Aug 1945At 1345 hours (zone -9), USS Aspro (Cdr. J.H. Ashley, Jr., USN), picked up a downed aviator inside Sagami Bay in position 35°11'N 139°20'E. While trying to pick up this survivor Aspro was attacked and bombed by Japanese aircraft but she sustained no damage.